Hey,
We have a grid with editors per cell. on a few computers, at one point, the users are getting the following error:
System.NullReferenceException: Object reference not set to an instance of an object.
at Infragistics.Win.ValueListDropDownAppearanceManager.ResolveValueListItemAppearance(ValueListItemUIElement valueListItemElement, AppearanceData& appData, AppearancePropFlags requestedProps)
at Infragistics.Win.ValueListItemUIElement.InitAppearance(AppearanceData& appearance, AppearancePropFlags& requestedProps)
at Infragistics.Win.ValueListItemUIElement.PositionChildElements()
at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)
at Infragistics.Win.UIElement.VerifyChildElements(Boolean recursive)
at Infragistics.Win.ControlUIElementBase.VerifyIfElementsChanged(Boolean verify, Boolean syncMouseEntered)
at Infragistics.Win.ControlUIElementBase.ProcessMouseHover(Object sender, EventArgs e)
at Infragistics.Win.Utilities.ProcessEvent(Control control, ProcessEvent eventToProcess, EventArgs e)
at Infragistics.Win.UltraControlBase.OnMouseHover(EventArgs e)
at System.Windows.Forms.Control.WndProc(Message& m)
at Infragistics.Win.ValueListDropDownUnsafe.WndProc(Message& message)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Thanks,
Mano
Hi Mano,
Without a sample or a lot more information, all I can do is take some really wild guesses here.
Is your application using threading? Are you creating any background threads? That might cause a problem like this.
Also, it is possible that you are using the same Editor or EditorControl for more than one grid? It's generally not a good practice to use a single editor in more than one control, although you can use the same one for more than one column or cell within the same grid.
What event(s) are you using to assign the editor to the cell(s)?
Are you handling other events that might be related to dropping down the list, like BeforeCellListDropDown or the DropDown event of the editor?
Are you populating the combo dynamically while the app is running, or just once up-front?
Thanks for your response.
We are using 13.2 but error also happened on old versions. I can't reproduce it on my computer. just on a very few computers. We have a few cells with a EditorWithCombo applied to. At one point when the user click to open the drop down, the error appeared.
Sorry, I can't replicate it,
Thank you for contacting Infragistics Developer Support.
I will need more information about your scenario as I couldn’t reproduce the issue on my machine. What version of our controls are you using? What editors are you using? Are there appearance objects assigned to the editors? What were the users doing when they got the exception? Can you provide me with concrete steps to reproduce it?
Also it would be extremely helpful if you are able to isolate the issue in a small sample or at least provide code snipped.
I am looking forward to your response.